1. Field of the Invention
Certain embodiments of the present invention relate to a battery adapter provided with a plurality of machine-side-connecting sections capable of being connected to a plurality of battery-connecting ports provided in an electric machine, and with a battery-side-connecting section to which a battery can be connected.
2. Description of the Related Art
Generally speaking, in an electric tool or an electric working device (hereinafter termed an electric machine), a battery that corresponds to a rated voltage of a motor of the electric machine is used. For example, in the case of an electric machine with a DC voltage of 36 volts, a battery with a DC voltage of 36 volts is usually used. However, batteries with a DC voltage of 36 volts are rather expensive and are not widely available in the market. In contrast, batteries with a DC voltage of 18 volts are generally used and widely available in the market.
U.S. Pat. No. 5,028,858 discloses an electric tool with a DC voltage of 36 volts that is constructed such that two batteries with a DC voltage of 18 volts can be connected to the electric tool. As shown in FIG. 14, an electric tool 100 as disclosed in the above-mentioned patent document is provided with two battery-connecting ports 103 so that two batteries 102 with a DC voltage of 18 volts can be connected to the ports 103. Further, the electric tool 100 includes an electric circuit for connecting the two batteries 102 in series. Thus, it is possible to drive an electric tool with a DC voltage of 36 volts by generally-used batteries with a DC voltage of 18 volts.
However, in an electric tool with a DC voltage of 36 volts provided with two battery-connecting ports (hereinafter termed as “a two-port electric tool”) for batteries with a DC voltage of 18 volts, it is impossible to use a battery with a DC voltage of 36 volts. Nor is it possible to drive a two-port electric tool with a DC voltage of 36 volts by a single battery with a DC voltage of 18 volts.
In this way, a two-port electric tool is not easy to use.